There is a great need for deodorizing compositions suitable for use in laundry applications. Some deodorants conceal unpleasant odors through the addition of perfumes. Others utilize antimicrobial active ingredients. Still others utilize odor absorbers which can chemically or physically bond the odor-forming compounds by adsorption or absorption, respectively. One representative of such an odor absorber is a zinc salt of ricinoleic acid, such as zinc ricinoleate.
Zinc ricinoleate can chemically bond to odor-intensive organic substances with sulfur or nitrogen containing functional groups such as mercaptans, thioethers, low molecular weight carboxylic acids, such as isovaleric acid, as well as amines. The ability of zinc ricinoleate to chemically bond to substances of this type and negate their odor causing potential permits zinc ricinoleate to be used in many areas of application. However, due to its polymeric salt structure, zinc ricinoleate can only be used directly to a limited degree. Zinc ricinoleate is a compound which is only sparingly soluble in customary solvents, including water. In order to obtain effective preparations, zinc ricinoleate must be used in combination with solvents, surfactants, and solubility promoters. The typical solvents used are mono- or polyhydric alcohols in the presence of high amounts of water. Customarily used highly ethoxylated solubility promoters are unable, even in high concentrations, to keep the zinc ricinoleate in solution.
In the past, hydrolyzed ene-adducts of ricinic fatty acids and maleic anhydride have been used. In addition, other promoters that have been used include partial esters of di- or polyhydroxyalkanes, mono- and disaccharides, polyethylene glycols or alkanolamines with the ene adducts of maleic anhydride formed onto at least monounsaturated carboxylic acids with a chain length of from 10 to 25 carbon atoms and acid numbers from 10 to 140, which are preferably buffered to pH values around 6.5 with amino and/or amido compounds, such as triethanolamine, or glycol esters of aspartic acid and of glutamic acid as a result of the formation of salt-like bonds. Preparations with these solubility promoters tend to be cloudy and result in precipitation of individual components even at very low water levels.
Currently, there is no known solution for utilizing zinc ricinoleate in single dose laundry detergent compositions due to flocculation and sedimentation of the zinc ricinoleate when added over 0.005% by weight on an active basis. This instability worsens when samples are placed into elevated temperature stability. Many commercial suppliers such as Burlington Chemical (Burco DEO 51 NM), ICT Chemicals (Flexisorb OD-300), and Evonik (Tego Sorb A30, Tego Sorb Conc 50) provide chemicals that include 30 to 50% by weight zinc ricinoleate with the other 50 to 70% being a proprietary mixture of water, surfactants, and other solvents. However, even at a use level of 0.005% active of zinc ricinoleate in a unit dose, the zinc ricinoleate is unstable and settles out of solution within days at temperatures above 100° F. and weeks at room temperature.
Without intending to be bound by any particular theory, it is believed that the primary driver of instability in such compositions is water content, i.e., water activity, which is extremely restricted in unit dose compositions as compared to other compositions. There simply is not enough available water to solvate the zinc ricinoleate in unit dose compositions versus other higher water content compositions. For example, although zinc ricinoleate can be used in compositions that have high water activities above about 0.95, such as High Density Detergents (HDD) laundry in a bottle compositions, it has not been shown to be able to be used in compositions having low water activities less than about 0.8, for the aforementioned reasons.
Accordingly, there remains an opportunity to develop a single dose laundry detergent composition that includes zinc ricinoleate and that performs well. Furthermore, other desirable features and characteristics of the present disclosure will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the disclosure.